/*
 * Copyright (C) 2011 by Anton Novikau
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.googlecode.gplaces.core;

import android.app.Activity;
import android.os.AsyncTask;

/**
 * Async task implementation that is safe to activity recreation on
 * configuration change or killing by TaskManager. The task holds activity
 * reference it's attached to. Attaching/Detaching activity is managed by
 * Application that have a cache of all async task that are in progress.
 * 
 * @author Anton Novikov
 */
public abstract class SafeAsyncTask<Params, Progress, Result> extends
        AsyncTask<Params, Progress, AsyncTaskResult<Result>> {

    protected static final String TAG = SafeAsyncTask.class.getSimpleName();

    protected Activity activity;

    private final GplacesApp application;

    /**
     * Creates an instance of SafeAsyncTask.
     * 
     * @param activity activity the task is attached to
     */
    public SafeAsyncTask(Activity activity) {
        this.activity = activity;
        this.application = (GplacesApp) activity.getApplication();
    }

    /**
     * Internal method used to attach/detach task from activity.
     * 
     * @param activity activity instance being attached/detached
     */
    final void setActivity(Activity activity) {
        if (activity == null) {
            onActivityDetached();
            this.activity = null;
        } else {
            this.activity = activity;
            onActivityAttached();
        }
    }

    /**
     * Callback that is called on activity attaching.
     */
    protected void onActivityAttached() {}

    /**
     * Callback that is called on activity detaching.
     */
    protected void onActivityDetached() {}

    /**
     * {@inheritDoc}
     */
    @Override
    protected void onPreExecute() {
        application.addTask(activity, this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void onPostExecute(AsyncTaskResult<Result> result) {
        application.removeTask(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void onCancelled() {
        application.removeTask(this);
    }

}
